Thursday, June 25, 2009


The midbrain is a small region of brain situated between the diencephalon and the pons. It contains a number of tracts of nerve fibers, which include the pyramidal tract, involved in the performance of motor skills. The midbrain also contains the nerve pathways between the cerebral hemispheres and the medulla oblongata, and the nuclei of the third and fourth cranial nerves.

The midbrain comprises the tectum, tegmentum, the ventricular mesocoelia, and the cerebral peduncles. Caudally the midbrain adjoins the pons, and rostrally it adjoins the thalamus and hypothalamus. The midbrain, or mesencephalon, develops from the middle section of the embryonic brain. The human midbrain is archipallian in origin, which means its general architecture is shared with the most ancient of vertebrates. Dopamine produced in the substantia nigra plays a role in motivation and habituation of species.